JP4842176B2 - Temperature measuring apparatus and temperature measuring method - Google Patents

Description

  The present invention relates to a temperature measuring apparatus and a temperature measuring method capable of accurately measuring the temperature of an object to be measured, for example, a front surface, a back surface, an inner layer, and the like of a semiconductor wafer and a liquid crystal substrate.

  For example, to accurately measure the temperature of a substrate to be processed, such as a semiconductor wafer, processed by a substrate processing apparatus, the shape of a film or a hole formed on the semiconductor wafer as a result of various processes such as film formation or etching It is also extremely important from the viewpoint of accurately controlling physical properties. For this reason, for example, the temperature of a semiconductor wafer has been conventionally measured by various methods such as a resistance thermometer or a measurement method using a fluorescence thermometer for measuring the temperature of the back surface of a substrate.

In recent years, a temperature measurement technique using a low coherence interferometer capable of directly measuring the wafer temperature, which has been difficult with the conventional temperature measurement method as described above, is known. Furthermore, in the temperature measurement technique using the low coherence interferometer, the light from the light source is divided into the measurement light for temperature measurement and the reference light by the first splitter, and the divided measurement light is further divided by the second splitter. The measurement light is divided into n measurement lights, and the n measurement lights are irradiated onto the n measurement points. The reflected light of the n measurement lights and the reflected light of the reference light reflected by the reference light reflecting means A technique has also been proposed in which interference is measured and the temperature at a plurality of measurement points can be measured simultaneously (see, for example, Patent Document 1). According to such a technique, the temperature of a plurality of measurement points can be measured at a time with a simple configuration.
JP 2006-112826 A

  With the conventional technology described above, the temperature at a plurality of measurement points can be measured at once with a simple configuration. However, with the above-described conventional technology, it becomes difficult to identify the measurement waveform from which the interference waveform is generated, particularly when the number of measurement points is large, and it may be difficult to detect temperature or may be erroneously detected. There is a problem.

  The present invention was made in response to such a conventional situation, and even when the number of measurement points is large, it is possible to identify the interference waveform from each measurement point and reliably detect the temperature, An object of the present invention is to provide a temperature measuring apparatus and a temperature measuring method capable of performing substrate processing and the like with high accuracy and efficiency.

  The temperature measurement device according to claim 1 further includes a light source, a first splitter for dividing light from the light source into measurement light and reference light, and n measurement light from the first splitter. A second splitter for dividing the first to n-th measurement light, a reference light reflecting means for reflecting the reference light from the first splitter, and an optical path length of the reference light reflected from the reference light reflecting means. Optical path length changing means for changing, reference light transmission means for transmitting the reference light from the first splitter to a reference light irradiation position for irradiating the reference light reflecting means, and first to first light from the second splitter First to n-th measurement light transmission means for transmitting the n-th measurement light to the measurement light irradiation positions for irradiating the first to n-th measurement points of the temperature measurement object, respectively, and the first to first of the temperature measurement object. The first through first reflections from the n measurement points a light detector for measuring interference between the n measurement light and the reference light reflected from the reference light reflecting means, and from the second splitter in the first to nth measurement lights, the temperature measurement object In the temperature measurement device in which the optical path lengths from the first to nth measurement points are different from each other, the first to nth measurement lights are irradiated to the first to nth measurement points of the temperature measurement object. The result of individually measuring the position of the interference peak for each of the first to nth measurement points in advance is stored as initial peak position data, and the position of the interference peak obtained during temperature measurement and the initial peak position data are stored. And a controller for calculating a temperature for each of the first to nth measurement points.

  The temperature measurement device according to claim 2 is the temperature measurement device according to claim 1, wherein the controller irradiates the first to n-th measurement light to the first to n-th measurement points of the temperature measurement object. When measuring the position of the interference peak for each of the first to n-th measurement points individually in advance, the optical path length of the reference light is changed over the entire range in which the optical path length can be changed by the optical path length changing means. The initial peak position data is obtained by continuously changing.

  The temperature measurement device according to claim 3 is the temperature measurement device according to claim 1 or 2, wherein the controller includes the first to nth measurement lights at the first to nth measurement points of the temperature measurement object. Square-turned waveform obtained by squaring the waveform obtained by the photodetector when individually measuring the position of the interference peak when the first to n-th measurement points are individually measured in advance. The center of gravity of the interference peak is obtained and set as the center position of the interference peak.

  The temperature measurement device according to claim 4 is the temperature measurement device according to any one of claims 1 to 3, wherein the temperature measurement object is a substrate to be processed to be processed by a substrate processing device, The 1st to nth measurement light transmission means are arranged in the substrate processing apparatus so that the 1st to nth measurement light is irradiated to the 1st to nth measurement points in the plane of the substrate to be processed. It is characterized by that.

  The temperature measurement method according to claim 5 further includes: a light source; a first splitter for dividing light from the light source into measurement light and reference light; and n measurement lights from the first splitter. A second splitter for dividing the first to n-th measurement light, a reference light reflecting means for reflecting the reference light from the first splitter, and an optical path length of the reference light reflected from the reference light reflecting means. Optical path length changing means for changing, reference light transmission means for transmitting the reference light from the first splitter to a reference light irradiation position for irradiating the reference light reflecting means, and first to first light from the second splitter First to n-th measurement light transmission means for transmitting the n-th measurement light to the measurement light irradiation positions for irradiating the first to n-th measurement points of the temperature measurement object, respectively, and the first to first of the temperature measurement object. The first through first reflections from the n measurement points a light detector for measuring interference between the n measurement light and the reference light reflected from the reference light reflecting means, and from the second splitter in the first to nth measurement lights, the temperature measurement object In the temperature measurement method using the temperature measurement device in which the optical path lengths from the first to nth measurement points are different from each other, the first to nth measurement points of the temperature measurement object are the first to nth measurement points. a step of acquiring, as initial peak position data, a result of individually measuring the position of the interference peak when irradiated with n measuring light in advance for each of the first to nth measurement points, and at the time of temperature measurement, the temperature measurement object The first to nth measurement points are compared with the position of the interference peak obtained by irradiating the first to nth measurement light with the first to nth measurement light, and the initial peak position data. Every Characterized by a step of calculating a degree.

  The temperature measurement method according to claim 6 is the temperature measurement method according to claim 5, wherein the first to n-th measurement light of the temperature measurement object is irradiated with the first to n-th measurement light. When the peak position is individually measured in advance for each of the first to nth measurement points, the optical path length changing means continuously changes the optical path length of the reference light for the entire range in which the optical path length can be changed. In this case, initial peak position data is acquired.

The temperature measurement method according to claim 7 is the temperature measurement method according to claim 5 or 6, wherein the first to n-th measurement light is irradiated to the first to n-th measurement points of the temperature measurement object. When the position of the interference peak is individually measured in advance for each of the first to nth measurement points, the center of gravity of the square-turned waveform obtained by squaring the waveform obtained by the photodetector is obtained. The center position of the interference peak.

  According to the present invention, even when the number of measurement points is large, it is possible to identify the interference waveform from each measurement point and reliably detect the temperature, and to perform substrate processing and the like more accurately and efficiently. It is possible to provide a temperature measuring apparatus and a temperature measuring method capable of performing the above.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially the same function structure, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 1 shows a schematic configuration of a temperature measuring apparatus 100 according to the present embodiment. As shown in FIG. 1, the temperature measurement device 100 includes a light source 110, a first splitter 120 for dividing light from the light source 110 into measurement light for measuring temperature and reference light, and the first splitter 120. The second splitter 130 for further dividing the measurement light into n first to n-th measurement lights, reference light reflecting means 140 for reflecting the reference light from the first splitter 120, and reference light reflection Optical path length changing means 150 for changing the optical path length of the reference light reflected from the means 140 is provided.

  The optical path length changing unit 150 includes, for example, a linear stage 151, a motor 152, a He-Ne laser encoder 153, and the like for moving the reference light reflecting unit 140 including a reference mirror in one direction parallel to the incident direction of the reference light. It is composed of Thus, by driving the reference mirror in one direction, the optical path length of the reference light reflected from the reference mirror can be changed. The motor 152 is controlled by the controller 170 via the motor controller 155 and the motor driver 154. The signal from the He-Ne laser encoder 153 is converted into a digital signal by the A / D converter 172 and input to the controller 170.

  Further, the temperature measuring apparatus 100 reflects the first to n-th measurement lights reflected from the temperature measurement object 10 when the first to n-th measurement points in the temperature measurement object 10 such as a semiconductor wafer are irradiated. A photodetector 160 is provided for measuring interference between the nth measurement light and the reference light reflected from the reference light reflecting means 140 when the reference light reflecting means 140 is irradiated with the reference light.

  As the light source 110, any light can be used as long as interference between the measurement light and the reference light can be measured. When measuring the temperature of a semiconductor wafer, for example, as the temperature measurement object 100, the light is such that the reflected light from at least the distance between the front surface and the back surface of the semiconductor wafer (usually about 800 to 1500 μm) does not cause interference. Is preferred. Specifically, for example, it is preferable to use low coherence light. Low coherence light refers to light with a short coherence length. The center wavelength of the low-coherence light is preferably 0.3 to 20 μm, for example, and more preferably 0.5 to 5 μm. Moreover, as coherence length, 0.1-100 micrometers is preferable, for example, and also 3 micrometers or less are more preferable. By using such low-coherence light as the light source 110, it is possible to avoid an obstacle due to extra interference and easily measure interference with reference light based on reflected light from the surface or inner layer of the semiconductor wafer. .

  As the light source using the low-coherence light, for example, SLD (Super Luminescent Diode), LED, high-intensity lamp (tungsten lamp, xenon lamp, etc.), ultra-wideband wavelength light source, etc. can be used. Among these low-coherence light sources, it is preferable to use a high-luminance SLD (wavelength, for example, 1300 nm) as the light source 110.

  For example, an optical fiber coupler is used as the first splitter 120. However, the present invention is not limited to this, and any light source that can be divided into reference light and measurement light may be used. For the second splitter 130, for example, an optical fiber coupler is used. However, the present invention is not limited to this, and any light source can be used as long as it can be divided into first to nth measurement beams. As the first splitter 120 and the second splitter 130, for example, an optical waveguide type demultiplexer, a semi-transparent mirror, or the like may be used.

  The reference light reflecting means 140 is constituted by a reference mirror, for example. As the reference mirror, for example, a corner cube prism, a plane mirror, or the like is applicable. Among these, it is preferable to use a corner cube prism from the viewpoint of parallelism with incident light of reflected light. However, as long as the reference light can be reflected, the configuration is not limited to the above, and may be configured with a delay line, for example.

  The light detector 160 is preferably configured using, for example, a photodiode in consideration of low cost and compactness. Specifically, for example, a PD (Photo Detector) using a Si photodiode, an InGaAs photodiode, a Ge photodiode, or the like is used. However, as long as the interference between the measurement light from the temperature measurement object 10 and the reference light from the reference light reflecting means 140 can be measured, the detection is not limited to the above, and for example, light detection is performed using an avalanche photodiode or a photomultiplier tube. The device 160 may be configured. The detection signal of the photodetector 160 is input to the A / D converter 172 via the amplifier 171, converted into a digital signal, and processed by the controller 170.

The reference light from the first splitter 120 is transmitted to the reference light irradiating position for irradiating the reference light reflecting means 140 via the reference light transmitting means such as the collimating fiber F _Z , and the reference light from the second splitter 130 is transmitted. The first to n-th measurement lights are transmitted to the measurement light irradiation position for irradiating the temperature measurement object 10 via the _first to _n- th measurement light transmission means, for example, collimating fibers F _{1 to} F _n. ing. The first to n-th measurement light transmission means is not limited to the collimate fibers F _{1 to} F _n, and may be, for example, a collimator-equipped optical fiber having a collimator attached to the tip of the optical fiber.

The temperature measurement apparatus 100 is configured such that the optical path lengths from the second splitter 130 to the temperature measurement object 10 in the first to n-th measurement lights are different from each other. Specifically, for example, when the lengths of the collimating fibers F _{1 to} F _n are the same, for example, the front end surfaces of the collimating fibers F _{1 to} F _n , that is, the measurement light irradiation position are in the irradiation direction from the temperature measurement object 10. It arrange | positions so that it may each slip | deviate to a substantially parallel direction. Further, without shifting the distal end surface of the collimating fiber F ₁ to F _n, by changing the length or the length of the optical fiber collimator fiber F ₁ to F _n, a second splitter in said first to n measuring beam The optical path lengths from 130 to the temperature measurement object 10 may be different.

  In the case where the first to nth measurement light transmission units are arranged to be shifted from the temperature measurement object 10, an interference wave between the first to nth measurement light and the reference light measured at least for each measurement point. It is necessary not to overlap each other. For example, when a low-coherence light source is used as the light source 110, if the first to n-th measurement light transmission units are arranged to be shifted from the temperature measurement object 10 by at least the coherence length of the interference wave, the interference wave overlaps. Can be prevented. Further, the position where the first to nth measurement light transmission units are disposed is determined in consideration of the thickness of the temperature measurement object, the rate of change of the thickness, the temperature range to be measured, the moving distance of the reference mirror, and the like. It is preferable to do. Specifically, for example, in the case of a silicon wafer having a thickness of about 0.7 mm, the moving distance of the reference mirror in the temperature range from room temperature to about 200 ° C. is about 0.04 mm. It is preferable to dispose the means from the temperature measurement object 10 by about 0.1 mm. Thereby, the interference wave for each measurement point can be prevented from overlapping.

  Thereby, the interference wave of the measurement point irradiated with each 1st-nth measurement light can be detected at a time only by scanning the reference light reflection means 140 once. For this reason, the time taken for temperature measurement can be shortened as much as possible.

In the temperature measurement apparatus 100 of the present embodiment, an attenuator 180 is provided as an optical attenuator in the optical path of the reference light further divided by the first splitter 120. The attenuator 180 is for attenuating the reference light so that the intensity of the reflected light of the reference light approaches the intensity of the reflected light of the first to nth measurement lights. Specifically, as shown in FIG. 1, it is possible to suitably use a device that attenuates the level of light passing therethrough, for example, to about (1 / n) ^1/2 .

When the attenuator 180 as described above is provided, the level of the reflected light of the reference light incident on the photodetector 160 is determined by passing the first splitter 120 twice when the light emitted from the light source 110 is 1. (1/2) ² , and 1 / n by passing through the attenuator 180 twice, approximately (1/2) ² × 1 / n. Note that the reflectance of the reference light reflecting means 140 is approximately 1.

On the other hand, the reflected light of the measurement light incident on the photodetector 160 becomes (1/2) ² by passing through the first splitter 120 twice with the reflectance of the temperature measurement object 10 being R, and the second splitter. By passing through 130 twice, (1 / n) ^{2 is obtained} (for example, 1/16 when n = 4), and since there are n reflectances R, approximately (1/2) ² × (1 / n) ² × R × n = (1/2) ² × 1 / n × R.

  Therefore, the difference between the level of the reflected light of the reference light and the level of the reflected light of the first to nth measurement lights is only the difference in the reflectance R of the temperature measurement object 10, and the second splitter 130 is substantially In the absence, that is, the same as the case of one-point measurement.

  That is, as shown in FIG. 2A, in the case of one-point measurement, if the intensity of the reflected light of the reference light is 1, the intensity of the reflected light of the measuring light is R, and the reference light included in the waveform to be measured The ratio of the measurement light is “reference light: measurement light = 1: R”.

  On the other hand, as shown in FIG. 2B, in the case of the conventional n-point measurement, if the intensity of the reflected light of the reference light is 1, the intensity of the reflected light of the measuring light is R × (1 / n). The ratio between the reference light and the measurement light included in the waveform to be calculated is “reference light: measurement light = 1: R × (1 / n)”. For this reason, when the number of n increases, the difference in level of reference light and measurement light becomes large. Since the interference intensity is determined by the intensity of the measurement light, if the difference between the levels of the reference light and the measurement light increases, the interference intensity is buried in the reference light intensity, and the S / N ratio decreases.

On the other hand, as shown in FIG. 2C, in the temperature measurement apparatus 100 of the present embodiment, the intensity of the reflected light of the reference light is attenuated to 1 / n by the attenuator 180, and therefore the waveform to be measured. The ratio of the reference light and the measurement light included in the sample is “reference light: measurement light = 1: R”, which is the same as in the case of one-point measurement, and thus the S / N ratio compared to the case of FIG. Can be improved. In the present embodiment, the case where the light level is attenuated to (1 / n) ^1/2 as the attenuator 180 has been described. However, the present invention is not limited to this, and the attenuation level can be appropriately selected. .

  Next, a second embodiment will be described with reference to FIG. The temperature measuring apparatus 200 shown in FIG. 3 uses only one splitter 220 to separate the light from the light source 110. The splitter 220 divides the light from the light source 110 into first to nth measurement light and n + 1 light of reference light. Other configurations are the same as those of the temperature measuring apparatus 100 of FIG.

For this temperature measuring device 200, as shown in FIG. 2 (d), the ratio of the reference light and the measurement light in the wave to be measured, "reference beam: measuring beam = 1: R × n" that Do and .

  Next, a third embodiment will be described with reference to FIG. 4 is an AC component extraction unit that extracts an AC component (AC component) from the detection signal of the photodetector 160 in place of providing the attenuator 180 in the temperature measurement device 100 shown in FIG. 310 is provided. The AC component extraction means 310 can be switched between a state in which AC components are extracted by the switch 311 and a state in which all signals are allowed to pass so that the DC level (light intensity) can be confirmed. Other configurations are the same as those of the temperature measuring apparatus 100 of FIG.

  In the case of this temperature measuring apparatus 300, by extracting the AC component by the AC component extracting means 310, the interference intensity at the AC level can be measured regardless of the magnitude of the DC level. Thereby, the S / N ratio can be improved as compared with the case of FIG.

Next, a temperature measuring device 400 and a temperature measuring device 500 that can measure the temperature in each processing chamber of a substrate processing apparatus having a plurality of processing chambers will be described with reference to FIGS. The temperature measuring device 400 shown in FIG. 5 switches a plurality of, for example, six processing chambers PC1, PC2,..., PC6 by a switch 410, for example, an optical add / drop multiplexer (OADM). The temperature of the substrate to be processed placed inside and, if necessary, the focus ring F / R can be measured. That is, the second splitter 130 and the first to n-th measurement light transmission means, for example, collimated fibers F _{1 to} F _n (n = 4 in FIGS. 5 and 6) are provided in the respective processing chambers PC1, PC2,. A switch 410 is provided between the six second splitters 130 and the first splitter 120. Then, the temperature of each of the processing chambers PC1, PC2,... PC6 can be measured by selecting the processing chambers PC1, PC2,. In each processing chamber PC1, PC2,..., PC6, processing such as etching and film formation is performed on a substrate to be processed, for example, a semiconductor wafer.

  Further, the temperature measuring apparatus 500 shown in FIG. 6 inserts the third splitter 510 between the first splitter 120 and the second splitter 130 for a plurality of, for example, six processing chambers PC1, PC2,. The light from the light source is divided and supplied to the second splitter 130 of the six processing chambers PC1, PC2,..., PC6 so that the temperature of the substrate to be processed and the focus ring can be measured. It is.

  In the temperature measuring device 400 and the temperature measuring device 500 described above, the light source 110, the first splitter 120, the reference light reflecting means 140, the optical path length changing means 150, the photodetector 160, the controller 170, etc. are connected to the processing chambers PC1, PC2,. ... Since the temperature can be measured in common with the PC 6, an increase in cost can be suppressed as compared with a case where a temperature measuring device is provided for each processing chamber. In addition, since data related to measurement can be centrally managed by one controller 170, labor and cost required for data management can be reduced.

  In this case, the controller 170 stores data on the interference position for each processing chamber PC1, PC2,... PC6 in advance, and calls the data on the interference position for each processing chamber PC1, PC2,. use. In addition, when measuring temperatures at a plurality of measurement points in each of the processing chambers PC1, PC2,..., PC6, data on the interference position for each measurement point is stored, and the data on the interference position is stored in the processing chamber PC1. , PC2, ... Call and use each PC6.

  Next, a method for measuring the interference position (initial peak position) at each measurement point will be described. First, as shown in FIG. 7, the wafer piece 602 is placed on the wafer mounting table 601 so that the reflected light is detected only from the measurement point (channel 1 in FIG. 7) for measurement. Alternatively, as shown in FIG. 8, for other measurement points, holes are opened and there is no reflected light from other measurement points, and reflected light is detected only from the measurement point (channel 1 in FIG. 8) for measurement. The perforated wafer 603 configured as described above is placed on the wafer mounting table 601. Alternatively, as shown in FIG. 9, processing is performed on the back surface in which reflection of light is reduced at other measurement points and strong reflected light is detected only from the measurement point (channel 1 in FIG. 9). The applied back surface processed wafer 604 is placed on the wafer mounting table 601. For example, only the reflected light from one measurement point (channel 1) for measurement can be detected.

  Next, under the control of the controller 170, the initial peak position is detected as follows. As shown in the flowchart of FIG. 10, first, the number of channels, stage speed, measurement pitch, initial temperature, port number, peak detection range, peak approximation range, up to which peak to use, the channel to be measured, and the expected arrival temperature Are input (701), and measurement is started (702).

  Next, the controller 170 starts to move the linear stage 151 to the non-motor limit (position where the optical path length of the reference light is the shortest optical path length), and monitors the stage position and driving state. (703) When the movement is completed, the driving is stopped (704).

  Next, movement is started so as to move the linear stage 151 in the motor side limit direction (705), and sampling from the A / D converter 172 is started (706). At this time, the number of samplings is calculated so that sampling stops before the limit.

  When the sampling is completed (707), the linear stage 151 starts decelerating and stopping (708), and the driving of the linear stage 151 is stopped (709).

  Next, the movement is started so that the linear stage 151 is moved to the non-motor side limit (710).

Then, waveform analysis is performed to calculate an initial peak position, an initial stage position, and a waveform measurement distance. In addition,
Maximum peak detection distance−minimum peak detection distance + stage acceleration / deceleration distance = waveform measurement distance. The result is stored for each channel, and the waveform is displayed (711).

  Next, it is determined whether or not there is a peak position overlap (712). If there is no peak position overlap, normal is displayed (713), and if there is a peak overlap, an alarm is displayed (714).

  Next, it is determined whether or not to measure another channel (715). When the other channel is measured, the above process is repeated. When there are no more channels to be measured, the process is terminated (716).

  FIG. 11 shows an example of a measurement waveform obtained for one measurement point (channel) as described above. In FIG. 11, the vertical axis represents the output of the photodetector, and the horizontal axis represents the moving distance of the mirror as the reference light reflecting means. In the above-described initial peak position detection method, the linear stage 151 is moved from the limit position (position where the optical path length of the reference light is the shortest optical path length) from one side (the side opposite to the motor in FIG. 1 and the like) for the entire drive range. Since the sampling is performed, the peak position can be detected without knowing the thickness of the temperature measurement object 10. For the first peak, the maximum value is detected from all the data, and the peak center is detected at the position of the maximum value ± the width of an arbitrary value (μm) to obtain the peak position. For the second peak, the maximum value is detected among all the data from the next of the closing price of the first peak detection width, and the peak center is detected at the position of this maximum value ± width of an arbitrary value (μm). Position. For the third peak, the maximum value is detected among all the data from the next of the closing price of the second peak detection width, and the peak center is detected at the position of the maximum value ± the width of an arbitrary value (μm). Position. The detection of the peak center is performed, for example, by obtaining the position of the center of gravity of the square folded waveform obtained by squaring the raw waveform.

  FIG. 12 shows an example of waveform data obtained for each measurement point (CH1 to CH3) as described above. In FIG. 12, the vertical axis represents the output of the photodetector, and the horizontal axis represents the moving distance of the mirror as the reference light reflecting means. As shown in the figure, by adjusting the optical path length so that the peak positions do not overlap, the peak from each measurement point can be identified as shown at the bottom of FIG.

  After detecting the initial peak position as described above, the initial thickness measurement of the temperature measurement object is performed prior to the temperature measurement. The temperature of the temperature measurement object is detected by a change in the thickness of the temperature measurement object with respect to the initial thickness. This initial thickness measurement will be described with reference to FIG. First, the number of channels, the stage speed, the measurement pitch, the port number, and the initial temperature are input and the number of times to average is selected (801).

  Next, it is determined whether to manually input the initial thickness and temperature (802), and when the initial thickness and temperature are known and input manually, processing from step 816 described later is performed. On the other hand, if not manually input, measurement is started (803), and initial position data and measurement distance data for each measurement point (channel) are called (804).

  Next, the movement of the linear stage 151 to the minimum start position between channels is started (805). When the linear stage 151 reaches the minimum start position between channels, the movement of the linear stage 151 in the motor side limit direction is started next. (806).

  Then, the A / D converter 172 is started (807) and sampling is started (808). At this time, the number of samplings is calculated so that sampling is stopped at the maximum inter-channel waveform measurement distance + α.

  When sampling is completed (809), deceleration of the linear stage 151 is started (810), and driving of the linear stage 151 is stopped (811).

  Next, the linear stage 151 is started to move to the minimum start position between channels (812).

Then, call the initial peak position of each measurement channel performs waveform analysis, the peak position, the peak position interval, the waveform display performed (81 3).

  Next, it is determined whether or not the linear stage 151 has reached the minimum start position between channels (814), and whether or not the measurement has been repeated a set number of times (815). Is obtained (816), and a temperature measurement start waiting state is entered (817).

  If the measured initial thickness and temperature as described above are known, by manually inputting them (802), an average of peak intervals is obtained (816), and a temperature measurement start waiting state is entered ( 817).

  As described above, the temperature can be measured after detecting the initial peak position and measuring the initial thickness. This temperature measurement will be described with reference to FIG. In this case, the temperature measurement start waiting state is maintained with the initial thickness measurement setting state described above being maintained (901). First, the data storage destination, the number of measurements, and the range of peak approximation are input (902).

  When the above input is completed, measurement is started (903), movement of the linear stage 151 to the minimum start position between channels is started (904), and when the linear stage 151 reaches the minimum start position between channels, the linear stage 151 The movement in the motor side limit direction is started (905).

  Then, the A / D converter is started (906), and sampling is started (907). At this time, the number of samplings is calculated so that sampling is stopped at the maximum inter-channel waveform measurement distance + α.

  When sampling is completed (908), deceleration of the linear stage 151 is started (909), and driving of the linear stage 151 is stopped (910).

  Next, the movement is started so as to move the linear stage 151 to the minimum start position between channels (911).

  Then, the waveform analysis is performed, the peak position interval is calculated from the peak position, the temperature is calculated from the peak position interval, the waveform is displayed, and the measurement data is saved (912).

  Next, it is determined whether the linear stage 151 has reached the minimum start position between channels (913), whether the measurement has been repeated by the set number of measurements (914), and the above measurement is repeated by repeating the set number of measurements. After the measurement, the measurement is finished (915).

  Next, as shown in FIGS. 5 and 6, processing in the temperature measuring device 400 and the temperature measuring device 500 that can measure the temperatures in the plurality of processing chambers will be described. FIG. 15 shows a method for detecting the initial peak position under the control of the controller 170 described above. In this case, first, the number of the processing chamber (PC) is selected (750). Steps 751 to 765 of the subsequent processing are substantially the same as steps 701 to 715 shown in FIG. However, in step 761, data such as the initial peak position is stored for each measurement channel with respect to the number of the selected processing chamber (PC). Then, at the end of the series of processes, it is determined whether to measure another process chamber (PC) (766), and the measurement is completed (767).

FIG. 16 shows a temperature measuring device 400 that can measure temperatures in a plurality of processing chambers, and a method for detecting initial thickness measurement by the control of the controller 170 in the temperature measuring device 500 described above. In this case, first, the number of the processing chamber (PC) is selected (850). Steps 851 to 866 of the subsequent processing are substantially the same as steps 801 to 816 shown in FIG. However, in step 854, the initial position data for each measurement channel corresponding to the number of the selected processing chamber (PC) is called. Further, in Step 8 6 3 calls the initial peak position of each measurement channel corresponding to number of selected process chamber (PC). Then, at the end of the series of processing, it is determined whether to measure another processing chamber (PC) (867), and a temperature measurement start waiting state is entered (868).

  As for the temperature measurement from the temperature measurement start waiting state (868) in FIG. 16, the temperature measurement apparatus 400 and the temperature measurement apparatus 500 that can measure the temperatures in the plurality of processing chambers are also described in FIG. This is performed in the same manner as the processing steps shown in FIG.

  In the temperature measuring apparatus 100 and the like, light from the light source 110 is incident on the first splitter 120 and is divided into measurement light and reference light by the first splitter 120. Among these, the measurement light is divided into first to n-th measurement lights by the second splitter 130 and irradiated to the temperature measurement object 10 or the like such as a semiconductor wafer at each measurement point. Or reflected by the back.

  On the other hand, the reference light is reflected by the reference light reflecting means 140. Then, each reflected light of the first to n-th measurement lights enters the first splitter 120 via the second splitter 130 and is detected by the photodetector 160 together with the reflected light of the reference light.

  Then, by scanning the reference light reflecting means 140, an interference waveform as shown in FIG. 12 is obtained with the vertical axis representing the output of the photodetector 160 and the horizontal axis representing the movement distance of the reference light reflecting means 140. Here, as the light source 110, the low-coherence light source as described above is used. According to the low-coherence light source, since the coherence length of the light from the light source 110 is short, usually strong interference occurs at a place where the optical path length of the measurement light and the optical path length of the reference light coincide with each other, and interference occurs at other places. It has the characteristic of being substantially reduced. For this reason, by moving the reference light reflecting means 140 and changing the optical path length of the reference light, in addition to the surface and the back surface of the temperature measurement object 10, if there are further layers inside, each of these layers is also refracted. The measurement light reflected by the rate difference interferes with the reference light.

  In the example of FIG. 12, when the reference light reflecting means 140 is scanned, first, interference between reflected light from one surface (front surface or back surface) of the measurement point P1 of the temperature measurement object 10 and reflected light of the reference light. A wave appears, and then an interference wave appears between the reflected light from one surface (front surface or back surface) of the measurement point P2 and one surface (front surface or back surface) of the measurement point P3 and the reflected light of the reference light. Further, when the reference light reflecting means 140 is scanned, an interference wave between reflected light from the interface of the intermediate layer of the measurement points P1, P2, and P3 and reflected light of the reference light appears. Finally, an interference wave appears between the reflected light from the other surface (back surface or front surface) of the measurement points P1, P2, and P3 and the reflected light of the reference light. Thus, the interference wave at each measurement point can be detected at a time only by scanning the reference light reflecting means 140 once.

  Next, a method for measuring the temperature based on the interference wave between the measurement light and the reference light will be described. As a temperature measuring method based on the interference wave, for example, there is a temperature conversion method using a change in optical path length based on a temperature change. Here, a temperature conversion method using the positional deviation of the interference waveform will be described.

  When the temperature measurement object 10 such as a semiconductor wafer is heated by a heater or the like, the temperature measurement object 10 expands and the refractive index changes, so that the position of the interference waveform is shifted before and after the temperature change, The peak-to-peak width of the interference waveform changes. At this time, if there is a temperature change for each measurement point, the position of the interference waveform shifts for each measurement point, and the peak-to-peak width of the interference waveform changes. A temperature change can be detected by measuring the peak-to-peak width of the interference waveform at each measurement point. For example, in the case of the temperature measuring apparatus 100 as shown in FIG. 1, the peak-to-peak width of the interference waveform corresponds to the movement distance of the reference light reflecting means 140. By measuring the temperature change can be detected.

  When the thickness of the temperature measurement object 10 is d and the refractive index is n, the deviation of the peak position for the interference waveform depends on the linear expansion coefficient α specific to each layer for the thickness d, and the refractive index n Is mainly dependent on the temperature coefficient β of the refractive index change specific to each layer. It is known that the temperature coefficient β of refractive index change also depends on the wavelength.

  Therefore, the wafer thickness d ′ after the temperature change at a certain measurement point P is expressed by the following equation (1). In Equation (1), ΔT indicates the temperature change at the measurement point, α indicates the linear expansion coefficient, and β indicates the temperature coefficient of the refractive index change. D and n represent the thickness and refractive index at the measurement point P before the temperature change, respectively.

d ′ = d · (1 + αΔT), n ′ = n · (1 + βΔT) (1)
As shown in the above formula (1), the optical path length of the measurement light that passes through the measurement point P changes due to the temperature change. The optical path length is generally represented by the product of the thickness d and the refractive index n. Therefore, if the optical path length of the measurement light transmitted through the measurement point P before the temperature change is L, and the optical path length after the temperature at the measurement point is changed by ΔT is L ′, L and L ′ are respectively the following formulas: As shown in (2).

L = d · n, L ′ = d ′ · n ′ (2)
Accordingly, when the difference (L′−L) in the optical path length of the measurement light at the measurement point before and after the temperature change is calculated and organized by the above formulas (1) and (2), the following formula (3) is obtained. . In addition, in the following mathematical formula (3), in consideration of α · β << α and α · β << β, minute terms are omitted.

L′−L = d ′ · n′−d · n = d · n · (α + β) · ΔT
= L · (α + β) · ΔT ₁ (3)

  Here, the optical path length of the measurement light at each measurement point corresponds to the peak-to-peak width of the interference waveform with the reference light. Therefore, if the linear expansion coefficient α and the temperature coefficient β of the refractive index change are examined in advance, by measuring the peak-to-peak width of the interference waveform with the reference light at each measurement point, using the above formula (3), It can be converted into the temperature at each measurement point.

  Thus, when converting from interference wave to temperature, the optical path length expressed between the peaks of the interference waveform varies depending on the linear expansion coefficient α and the temperature coefficient β of the refractive index change as described above. It is necessary to investigate in advance α and the temperature coefficient β of the refractive index change. In general, the linear expansion coefficient α and the temperature coefficient β of refractive index change of materials including a semiconductor wafer may depend on the temperature depending on the temperature range. For example, the linear expansion coefficient α generally does not change so much in the temperature range of about 0 to 100 ° C., so it can be regarded as constant. However, in the temperature range of 100 ° C. or higher, the temperature increases depending on the material. Since the rate of change may be large, the temperature dependency cannot be ignored in such a case. Similarly, the temperature dependence β of the refractive index change may not be negligible depending on the temperature range.

  For example, in the case of silicon (Si) constituting a semiconductor wafer, it is known that the linear expansion coefficient α and the temperature coefficient β of refractive index change can be approximated by, for example, a quadratic curve in a temperature range of 0 to 500 ° C. . Thus, since the linear expansion coefficient α and the temperature coefficient β of the refractive index change depend on the temperature, for example, the linear expansion coefficient α and the temperature coefficient β of the refractive index change corresponding to the temperature are examined in advance and the values are taken into consideration. If the temperature is converted, it can be converted to a more accurate temperature.

  Note that the temperature measurement method based on the interference wave between the measurement light and the reference light is not limited to the method described above. For example, a method using an absorption intensity change based on a temperature change may be used. A method in which an optical path length change based on the above and an absorption intensity change based on a temperature change are combined may be used.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

1 is a block diagram showing a schematic configuration of a temperature measurement device according to an embodiment of the present invention. The figure for demonstrating the relationship between the intensity | strength of reference light, and the intensity | strength of measurement light. The block diagram which shows schematic structure of the temperature measurement apparatus concerning other embodiment of this invention. The block diagram which shows schematic structure of the temperature measurement apparatus concerning other embodiment of this invention. The block diagram which shows schematic structure of the temperature measurement apparatus concerning other embodiment of this invention. The block diagram which shows schematic structure of the temperature measurement apparatus concerning other embodiment of this invention. The figure for demonstrating the method to detect an initial peak position. The figure for demonstrating the method to detect an initial peak position. The figure for demonstrating the method to detect an initial peak position. The flowchart for demonstrating the method to detect an initial peak position. The figure for demonstrating the method to detect an initial peak position. The figure for demonstrating the method to detect an initial peak position. The flowchart for demonstrating the method to detect initial thickness. The flowchart for demonstrating the method to detect temperature. The flowchart for demonstrating the method to detect the initial peak position in a multiple processing chamber. The flowchart for demonstrating the method to detect the initial thickness in a multi-processing chamber.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Temperature measuring object, 100 ... Temperature measuring device, 110 ... Light source, 120 ... 1st splitter, 130 ... 2nd splitter, 140 ... Reference light reflection means, 150 ... Optical path length change means, 151: Linear stage, 152: Motor, 153: He-Ne laser encoder, 154 ... Motor driver, 155 ... Motor controller, 160 ... Photo detector, 170 ... Controller, 171 ... Amplifier, 172 ... A / D converter, 180 ... Attenuator.

Claims (7)

A light source;
A first splitter for separating light from the light source into measurement light and reference light;
A second splitter for further dividing the measurement light from the first splitter into n first to n-th measurement lights;
Reference light reflecting means for reflecting reference light from the first splitter;
An optical path length changing means for changing an optical path length of the reference light reflected from the reference light reflecting means;
Reference light transmission means for transmitting the reference light from the first splitter to a reference light irradiation position for irradiating the reference light reflecting means;
First to n-th measurement light transmission means for transmitting the first to n-th measurement lights from the second splitter to the measurement light irradiation positions for irradiating the first to n-th measurement points of the temperature measurement object, respectively;
A photodetector for measuring interference between the first to n-th measurement light reflected from the first to n-th measurement points of the temperature measurement object and the reference light reflected from the reference light reflecting means; ,
In the temperature measurement device in which the optical path lengths from the second splitter to the first to n-th measurement points of the temperature measurement object in the first to n-th measurement lights are different from each other,
The result of individually measuring the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points individually for each of the first to n-th measurement points. Is stored as initial peak position data, and the controller calculates the temperature for each of the first to nth measurement points by comparing the position of the interference peak obtained at the time of temperature measurement with the initial peak position data. A temperature measuring device characterized by. The temperature measuring device according to claim 1,
The controller individually separates the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points for each of the first to n-th measurement points. In the measurement, the optical path length changing means continuously changes the optical path length of the reference light over the entire range in which the optical path length can be changed, and obtains initial peak position data. apparatus. The temperature measuring device according to claim 1 or 2,
The controller individually separates the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points for each of the first to n-th measurement points. A temperature measuring apparatus characterized in that, when measuring, a center of gravity of a square-turned waveform obtained by squaring the waveform obtained by the photodetector is obtained as a center position of an interference peak. The temperature measuring device according to any one of claims 1 to 3,
The temperature measurement object is a substrate to be processed by a substrate processing apparatus, and the first to nth measurement light transmission units are respectively connected to the first to nth measurement points in the plane of the substrate to be processed. The temperature measuring apparatus is disposed in the substrate processing apparatus so as to be irradiated with the first to n-th measuring lights. A light source;
A first splitter for separating light from the light source into measurement light and reference light;
A second splitter for further dividing the measurement light from the first splitter into n first to n-th measurement lights;
Reference light reflecting means for reflecting reference light from the first splitter;
An optical path length changing means for changing an optical path length of the reference light reflected from the reference light reflecting means;
Reference light transmission means for transmitting the reference light from the first splitter to a reference light irradiation position for irradiating the reference light reflecting means;
First to n-th measurement light transmission means for transmitting the first to n-th measurement lights from the second splitter to the measurement light irradiation positions for irradiating the first to n-th measurement points of the temperature measurement object, respectively;
A photodetector for measuring interference between the first to n-th measurement light reflected from the first to n-th measurement points of the temperature measurement object and the reference light reflected from the reference light reflecting means; ,
In the temperature measurement method using the temperature measurement device in which the optical path lengths from the second splitter to the first to n-th measurement points of the temperature measurement object in the first to n-th measurement lights are different from each other,
The result of individually measuring the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points individually for each of the first to n-th measurement points. To obtain the initial peak position data,
At the time of temperature measurement, the position of the interference peak obtained by irradiating the first to n-th measurement points to the first to n-th measurement points of the temperature measurement object is compared with the initial peak position data. And a step of calculating a temperature for each of the first to nth measurement points. The temperature measuring method according to claim 5,
When individually measuring the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points individually for each of the first to n-th measurement points. In addition, the optical path length changing means continuously changes the optical path length of the reference light for the entire range in which the optical path length can be changed, and acquires initial peak position data. The temperature measuring method according to claim 5 or 6,
When individually measuring the position of the interference peak when the first to n-th measurement points of the temperature measurement object are irradiated with the first to n-th measurement points individually for each of the first to n-th measurement points. And a center of the interference peak obtained by obtaining the center of gravity of the square-turned waveform obtained by squaring the waveform obtained by the photodetector.

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